About the mi² to ft² calculation
One square mile is exactly 27,878,400 square feet, so converting between them is a single multiplication. Enter any value above and the result updates as you type. Used for land and territory area in the US and UK. One square mile is exactly 640 acres. How property floor area is quoted in the US, UK and India.
Formula
ft² = mi² × 27,878,400
1 mi² = 27,878,400 ft²
1 ft² = 3.5870e-8 mi²Worked example
To convert 1 mi², multiply by 27,878,400: 1 × 27,878,400 = 27,878,400 ft².
Frequently asked questions
How many square feet are in a square mile?
There are 27,878,400 square feet in one square mile. To convert any amount, multiply the number of square miles by 27,878,400.
How do I convert square feet back to square miles?
Divide instead of multiplying, or equivalently multiply by 3.5870e-8. One square foot is 3.5870e-8 square miles.
Is this conversion exact?
Yes. Since the international agreement of 1959, the relationship between square miles and square feet is defined exactly rather than measured, so the only rounding here is in how many decimal places we show.
Where is each of these units used?
Square Miles: used for land and territory area in the US and UK. One square mile is exactly 640 acres. Square Feet: how property floor area is quoted in the US, UK and India.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units